From Bette Davis in 1939's "Dark Victory" to Nicole Kidman in the recent hit "Moulin Rouge," the disease was always fatal. Sometimes the writers didn't even specify what the ailment was -- all that mattered was that it was terminal. Spoofing these tragic melodramas on her television variety show, Carol Burnett provided the syndrome with an appropriate name: Movie Star Disease.

Shaping public perceptions has always been a powerful side effect of films and television. But when Hollywood portrays disease, the results can be laughably inaccurate -- or they can fuel fear, misunderstandings and prejudice.

Does Hollywood ever get it right?

The Comedy Writer's Favorite Disease

Perhaps no disease fares worse on television and in films than Tourette syndrome, a neurological disorder marked by involuntary muscle twitches and tics.

To most of the viewing public, however, TS has only one symptom: barking out obscenities at the worst possible moment, like when an elderly matron has entered the scene.

Though it's a boon to screenwriters, this obscene shouting -- known as coprolalia -- is rare even among those with TS. By most estimates, 80 percent to 90 percent of those with TS do not exhibit coprolalia.

Coprolalia has been played for laughs in countless television programs and in films like "Deuce Bigelow: Male Gigolo" and "Not Another Teen Movie." But for those who suffer from TS and those who are trying to raise awareness of the illness, there's nothing funny about it.

"It's extremely hurtful, especially for kids, who are bullied and made fun of," said Tracy Colletti-Flynn, spokeswoman for the Tourette Syndrome Association.

Campaign Fights Misperception

The association has embarked on a public awareness campaign to combat widespread misunderstanding of TS.

Actress Neve Campbell, whose brother Damien has TS, is spearheading the effort within the entertainment industry to raise the profile of those who live with the disease.

A public service announcement titled "It Ain't Funny & It Ain't True" has appeared in The Hollywood Reporter and Variety. The ad describes the ways that comic portrayals of TS encourage discrimination against those with even mild cases of the illness.

Cancer -- the Not-So-Big 'C'

For screenwriters scouting around for a slow and tragic death, no disease has had the staying power of cancer.

But few writers -- and even fewer viewers -- realize that many forms of cancer are treatable and the success rate for patients can be quite high. Films like "Brian's Song," "Terms of Endearment" and "Autumn in New York," however, would convince anyone that cancer is always a terminal illness.

"More patients every year are being cured of cancer -- but you don't see that," said Dr. Herman Kattlove, a medical oncologist with the American Cancer Society.

"Cancer is mainly used as a dramatic ploy," Kattlove said. "It's used as a way of bringing families together. But it's always about a terminal patient. People doing well doesn't make a good story."

Kattlove feels that the portrayal of cancer as an always-deadly disease creates an environment of fear, undermining the work of medical professionals who remind people that cancer today is usually not a death sentence.

"It does fuel a lot of unnecessary anxiety," he said. "It's not as deadly as it's portrayed in movies."

But Kattlove appreciates that movies are drama, not science.

"Their function is to make a good story, and a successful treatment of cancer usually isn't a good story," he said.

The 'Rain Man' Effect

Despite the casual relationship Hollywood has with medical facts, in at least one case the film industry has successfully encouraged public understanding of an illness and its effects.

The 1988 film "Rain Man," Dustin Hoffman portrays an autistic man who has been shunted away in an institution -- his own brother, played by Tom Cruise, is surprised to learn of his existence.

"In terms of awareness, there was a pre-'Rain Man' period and a post-'Rain Man' period," said Lee Grossman, president and chief executive officer of the Autism Society of America. "It contributed to people's knowledge of what autism is."

Grossman calls the institutionalization of Hoffman's character an accurate depiction of what many families once experienced when a child was diagnosed with autism. The film, Grossman believes, was responsible for encouraging more humane treatment of autistics.

"Up until that time, hardly anyone had ever heard of autism and most people with autism were being institutionalized or were warehoused at home," he said. "I think it had a very positive impact."

Sensationalizing Autism

The pendulum, however, may have swung too far in the other direction.

Many portrayals of autistics in film and television show characters with uncanny mathematical or musical gifts. Hoffman's character in "Rain Man" was blessed with a mind capable of performing trigonometric calculations that would make a NASA geek blush.

"They show kids with superhuman strength or brainiacs," said Grossman, who wishes media portrayals would more closely reflect the day-to-day realities of living with autism.

"People would like to portray this condition in a sensational manner," he said, "and it's just not that way."